1、Designation: D7314 10Standard Practice forDetermination of the Heating Value of Gaseous Fuels usingCalorimetry and On-line/At-line Sampling1This standard is issued under the fixed designation D7314; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is for the determination of the heatingvalue measurement of gaseous fuels us
3、ing a calorimeter.Heating value determination of sample gasses containing watervapor will require vapor phase moisture measurements of thepre-combustion sample gas as well as the non-condensedgasses exiting the calorimeter. Instruments equipped withappropriate conditioners and algorithms may provide
4、 heatingvalue results on a net or gross and dry or wet basis.1.2 This practice is applicable to at-line and in-line instru-ments that are operated from time to time on a continuousbasis.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thi
5、sstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Re
6、ferenced Documents2.1 ASTM Standards:2D1070 Test Methods for Relative Density of Gaseous FuelsD1826 Test Method for Calorific (Heating) Value of Gasesin Natural Gas Range by Continuous Recording Calorim-eterD3588 Practice for Calculating Heat Value, CompressibilityFactor, and Relative Density of Gas
7、eous FuelsD3764 Practice for Validation of the Performance of Pro-cess Stream Analyzer SystemsD4150 Terminology Relating to Gaseous FuelsD4891 Test Method for Heating Value of Gases in NaturalGas Range by Stoichiometric CombustionD5287 Practice for Automatic Sampling of Gaseous FuelsD5503 Practice f
8、or Natural Gas Sample-Handling and Con-ditioning Systems for Pipeline InstrumentationD6122 Practice for Validation of the Performance of Mul-tivariate Process Infrared Spectrophotometer Based Ana-lyzer SystemsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to
9、 Evaluate AnalyticalMeasurement System PerformanceD6621 Practice for Performance Testing of Process Analyz-ers for Aromatic Hydrocarbon MaterialsD7164 Practice for On-line/At-line Heating Value Determi-nation of Gaseous Fuels by Gas Chromatography2.2 ISO Standards:3ISO 14532 Natural gas VocabularyIS
10、O 7504 Gas analysis Vocabulary3. Terminology3.1 Definitions:3.1.1 at-line instrument, nSee Terminology D4150, Sec-tion 3.3.1.2 auto-verification, nan automated means of introduc-ing Calibration Gas Mixtures or Reference Gas Mixtures intoan analyzer for the purposes of verifying the analyzer response
11、without making any adjustments to the calibration parametersof the analyzer.3.1.3 bypass line, nLine ultimately vented to the atmo-sphere that is used where it is impractical to provide a sufficientpressure differential.3.1.3.1 DiscussionThe flowrate and pressure loss in theopen-ended line needs to
12、be controlled so as to ensure that thesample accuracy is not affected from any cooling and conden-sation or both (reference ISO 14532 paragraph 2.3.2.9).1This practice is under the jurisdiction of ASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.12 on On-Line/A
13、t-LineAnalysis of Gaseous Fuels.Current edition approved Jan. 1, 2010. Published February 2010. Originallyapproved in 2008. last previous edition approved in 2008 as D7314.-08 DOI:10.1520/D7314-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service a
14、t serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.1C
15、opyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.4 calibration gas mixture, na certified gas mixturewith known composition used for the calibration of a measur-ing instrument or for the validation of a measurement or gasanalytical m
16、ethod.3.1.4.1 DiscussionCalibration Gas Mixtures are the ana-logues of measurement standards in physical metrology (ref-erence ISO 7504 paragraph 4.1)3.1.5 calorimeter, nSee Terminology D4150, Section 3.3.1.6 continuous fuel monitor, nan instrument thatsamples gas directly from a source continuously
17、 and providesan analytical result on a continuous or semi-continuous basis.3.1.7 direct sampling, adjsampling where there is a directconnection between the sample source and the analytical unit,that is, in-line or on-line instrument.3.1.8 dry gas, nSee Terminology D4150, Section 3.3.1.9 fast loop/ho
18、t loop, nBypass loop that returnssampled gas to the process line in a closed configuration andused for environmental and safety considerations.3.1.9.1 DiscussionThe loop requires a pressure differen-tial from the collection point to the discharge point so as toensure a constant and steady flowrate t
19、hrough the samplingequipment located in the loop (reference ISO 14532 paragraph2.3.2.8)3.1.10 gross heating value (also called higher heatingvalue), nSee Terminology D4150, Section 3.3.1.11 heating value, nthe amount of energy per volumetransferred as heat from the complete, ideal combustion of theg
20、as at standard temperature.3.1.12 in-line instrument, nSee Terminology D4150, Sec-tion 3.3.1.13 net heating value (also called lower heating value),nSee Section 3 entitled Terminology, of D4150.3.1.14 on-line instrument, nSee Terminology D4150,Section 3.3.1.15 reference gas mixture, na certified gas
21、 mixturewith known composition used as a reference standard fromwhich other compositional data are derived.3.1.15.1 Discussion Reference Gas Mixtures are the ana-logues of reference standards (ISO 7504 paragraph 4.1.1)3.1.16 wet gas, nSee Terminology D4150, Section 3.3.2 Acronyms:3.2.1 SOP, nStandar
22、d Operating Procedure.3.2.2 QA, nQuality Assurance.4. Summary of Practice4.1 A representative sample of the gaseous fuel is extractedfrom a process pipe, a pipeline, or other gaseous fuel streamand is transferred to an analyzer sampling system. Afterconditioning that maintains the sample integrity,
23、the sample isintroduced into a calorimeter. Excess extracted process orsample gas is vented to the atmosphere, a flare header, or isreturned to the process in accordance with applicable economicand environmental requirements and regulations. Post-combustion gasses from the calorimeter are typically
24、vented tothe atmosphere.4.2 The heating value is calculated based upon the instru-ments response to changes in the heating value of the samplegas using an algorithm.4.3 Calibration (7.1), maintenance (Section 10), and perfor-mance (Section 9) protocols provide a means to validate andassess operation
25、 of the analyzer.5. Significance and Use5.1 On-line, at-line, in-line and other near-real time moni-toring systems that measure fuel gas characteristics such asheating value are prevalent in various gaseous fuel industriesand in industries either producing or using gaseous fuel in theirindustrial pr
26、ocesses. The installation and operation of particu-lar systems vary depending on process type, regulatory require-ments, and the users objectives and performance require-ments. This practice is intended to provide guidance forstandardized start-up procedures, operating procedures, andquality assuran
27、ce practices for calorimeter based on-line,at-line, in-line and other near-real time heating value monitor-ing systems. Users employing gas chromatographic basedinstrumentation for measurement of gaseous fuel heating valueare referred to Practice D7164.6. Apparatus6.1 InstrumentAny instrument of sta
28、ndard manufacture,with hardware necessary for interfacing to a fuel gas pipelineand containing all the features necessary for the intendedapplication(s) can be used.6.1.1 Combustion SystemOperating parameters employedmust be capable of converting all of the volatile combustiblechemical species in th
29、e sample into carbon dioxide, water,nitrogen, nitrogen dioxide, and/or sulfur dioxide, using a dry,hydrocarbon-free oxidant which is typically air. A change ofless than or equal to 1,000 ppm/wt in the moisture content ofinstrument air between calorimeter calibrations is acceptable tomaintain a stati
30、stically insignificant 6 0.1% heating valueaccuracy as denoted in Practice D4891. The less than 1,000ppm/wt moisture content control value is easily achieved usingdesiccant or refrigerant air dryers when the air dryers aremaintained according to the manufacturers recommendations.Instrumentation must
31、 satisfy or exceed analytic performancecharacteristics for accuracy and precision for the intendedapplication without encountering unacceptable interference orbias. In addition, components in contact with sample streamssuch as tubing and valving must be constructed of suitable inertor passivated mat
32、erials to ensure that the composition of thesampled gas is not altered.6.2 Sample Probes/Sample ExtractionThe location andorientation of sampling components are critical for ensuringthat a representative sample is analyzed. The locations andorientation of sampling components should be selected based
33、upon sound analytic and engineering considerations. Samplingpractices for gaseous fuels can be found in Practice D5287.6.3 Sample Inlet SystemAn automated gas sampling valveis required in many applications. All sampling system compo-nents in contact with the fuel stream must be constructed ofinert o
34、r passivated materials. Care should be taken to ensurethat the extracted sample is maintained in a single cleangaseous phase. The addition of heat at the point of pressurereduction or along the sample line to the analyzer may berequired to ensure that the sample is maintained in the gasphase. The ne
35、ed for heat tracing and the extent to which it isD7314 102required will be site specific. In general, considerations im-pacting heat tracing decisions include sample compositions andthe expected variations, ambient temperature fluctuations,operating pressures, and anticipated pressure differentials
36、insample system components. Sample filtration should be uti-lized as required to remove particulate matter from the ex-tracted sample.6.3.1 Combustion Air, Sample, and Carrier Gas ControlConstant flow control of combustion air, sample gas, andcarrier gas, if required by the measurement application,
37、isnecessary for optimum and consistent analytical performance.Control is typically achieved by use of pressure regulators andfixed flow restrictors. Ambient, combustion air, sample, andcarrier gas temperature control is generally vital for ensuringconsistent operation of flow control devices. The ga
38、s flow ismeasured and verified by appropriate means and adjusted asnecessary.6.3.2 DetectorsCommon calorimetry heating value detec-tion systems include stoichiometric combustion (Test MethodD4891), continuous recording calorimeters (Test MethodD1826), non-stoichiometric combustion, and residual oxyg
39、endetection calorimeters. Other detectors can be used providedthey have appropriate linearity, accuracy, sensitivity and mea-surement range for the selected application. In selecting adetector, the user should consider the linearity and sensitivityof a particular detection system prior to installati
40、on. The usershould also consider potential sample compositional effectsthat may influence the reported heating value.6.4 Data AcquisitionData acquisition and storage can beaccomplished using a number of devices and media. Followingare some examples:6.4.1 RecorderA 0 to 1 millivolt or a 4-20 milliamp
41、 rangerecording potentiometer or equivalent, with a full-scale re-sponse time of 2 s or less can be used mounted locally orremotely.6.4.2 Communications SystemsEfficient communicationsbetween the analyzer and the host depend on resolving any andall interface issues. Signals to and from the host are
42、typicallyisolated from each other in an appropriate manner.7. Reagents and Materials7.1 WarningCompressed gas standards should only behandled in well ventilated locations away from sparks andflames. Improper handling of compressed gas cylinders con-taining calibration standards or air can result in
43、explosion.Compressed air supports combustion.7.1.1 StandardsComponents in the Calibration Gas Mix-ture should be representative of the monitored gas. The heatingvalue is either determined instrumentally or is calculated usinga certified gas composition of the standard. Practice D3588 orother methods
44、 as required for regulatory purposes can be usedto calculate the heating value of a gas mixture. Other heatingvalue calculational algorithms can be used so long as allinterested parties are advised of and are in agreement with thecalculational methodology employed, or both. Methods relatedto determi
45、ning the relative density of gaseous fuels can befound in Practice D1070. Mixtures of major components aretypically specified to achieve the desired heating value. Aminimum of major representative components is frequentlyused. The number of components used is frequently minimizedfor economical reaso
46、ns and to reduce the probability of errorduring the preparation of the Calibration Gas Mixture. In orderto ensure their accuracy and stability by preventing condensa-tion and degradation, Calibration Gas Mixtures must be main-tained within the temperature range specified by the manufac-turer. If the
47、re is any doubt concerning the validity of theCalibration Gas Mixture, a Reference Gas Mixture should beused to verify the validity of the Calibration Gas Mixture.8. Equipment Siting and Installation8.1 The siting and installation of an at-line or on-linemonitor is critical for collecting representa
48、tive information onheating value content. Factors that should be considered insiting an instrument include hazardous area rating, ease ofcalibration, ease of access for repair or maintenance, sampleuniformity at the sampling point, appropriateness of samplesfrom a sampling location, ambient conditio
49、ns, and of coursesafety issues. A sample inlet system capable of operatingcontinuously at or above the maximum operating sampletemperature is necessary. The location of the sample inlet to theanalyzer relative to the sample extraction point is critical toobtaining timely analytical results. Ideally, the analyzer isclose-coupled to the sample extraction point and there is aninsignificant sampling lag time. Normally, the analyzer ismounted at some distance away from the sample extractionpoint. This increased distance will result in increased lag
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